Data communication networks are oftentimes used to interconnect data systems which use the networks to both send and receive data. Typically, such data communication networks may comprise ring transmission paths interconnecting ring interface nodes used to couple data systems with the ring transmission paths. In such a network data is usually transmitted from an originating data system to a ring interface node, oftentimes referred to simply as a node, and over a ring transmission path through intermediate nodes to a node coupled with a receiving data system.
Shift register type of data communication networks have been disclosed in the past where data is transmitted in a clockwise direction on one ring transmission path and in a counter clockwise direction on another ring transmission path. Such a system is analogous to an empty slot mechanism wherein individual frames of a fixed length keep circulating around a ring transmission path. In these types of networks a source node receiving data from an originating data system inserts the data into the circulating slots and a destination node removes the data from the circulating slot and transmits it to a receiving data system. Generally speaking these types of data communication networks require elaborate clocking schemes that shift the slots around the ring transmission path at a constant rate. Such networks may undesirably slow transmission of data when a large number of nodes are required to interconnect data systems.
Other types of data communication networks have nodes designed with register and by-pass circuitry wherein incoming data is both loaded into the register and by-passed around the node on the ring transmission path. The register and by-pass type of nodes oftentimes result in data that is addressed to a node and destined for a data system served by the addressed node to continue on the ring transmission path past the addressed or destination node. A problem arises with these types of data communication networks in that the flow of data past an addressed node unnecessarily increases the amount of data appearing on a ring transmission path and decreases the network data handling capabilities. In addition, these types of data communication networks require that the source node having originated the data, or a common node, be provided with ways to remove the bypassed data from the ring transmission path. Oftentimes this is accomplished by processor apparatus of the source node which must also perform the additional function of removing this data from a ring transmission path thereby resulting in a decrease in efficiency of the processor apparatus.
The foregoing and other problems are solved and a technical advance is achieved by a data communication network arranged to handle varying rates of data on ring transmission paths and by a node arranged to derive information defining the node disposition of incoming data and to dispose of the data in accordance with the derived disposition information without decreasing the data handling capabilities of the data communication network.